1. Field of the Invention
The present invention relates to a method and a production line for a laminate assembly formed by laminating thin plates, and in further detail, to a method and a production line for a laminate assembly having high accuracy in height by reflecting measurement data in the number of thin plates to be laminated of a newly laminated laminate assembly while measuring the lamination height of the laminate assembly press-worked and laminated.
2. Description of Related Art
For example, a motor core produced as an electric component is formed as a laminate assembly by punching out thin steel plates to a predetermined shape by press-working, laminating and caulking the same. A method has been known by Japanese Patent Publication No. 2720138, by which a laminated iron core used as a motor core is produced by forming caulking parts in respective laminated steel plates, which composes a laminate assembly, by means of cutting and lifting, and fitting the caulking parts, adjacent to each other, of the laminated steel plates which are stacked up under pressure.
The method for producing the laminated iron cores is able to produce the laminated iron cores without strain, damage to the coating on iron core pieces, and buckling without any gaps remaining between the laminated iron core pieces (punched-out laminated steel plates). The laminated iron cores have through-holes drilled left and right alternately toward the lamination direction at the end parts of the caulking parts of the laminated iron core pieces. The folded-over root part of the caulking part is positioned in the through-hole of the adjacent iron core pieces. Accordingly, there will be no cases where the inclined planes of the caulking parts of the adjacent laminated iron cores are brought into contact, wherein the lamination height is prevented from becoming high due to occurrence of gaps between the iron core pieces by the inclined planes being brought into contact.
However, although the laminated iron core described in the patent publication mentioned above prevents the lamination height thereof from becoming high by eliminating the gaps between respective iron core pieces which are laminated, there exists unevenness in plate thickness within the tolerance (an error in plate thickness within the dimensional tolerance) in the respective iron core pieces. Therefore, the unevenness in the plate thickness existing in the respective iron core pieces greatly influences the lamination height of the laminated iron cores which are stacked up, wherein when the laminated iron core is produced by laminating by the set number of thin plates, unevenness is brought about more or less in the lamination height of laminated iron cores produced.
Therefore, conventionally, in order to secure a set lamination height, the thickness of before-machining iron core pieces (laminated steel plate) was measured, the set lamination height was divided by the thickness of the iron core pieces, the number of thin plates to be laminated was calculated and set. However, since the plate thickness of the iron core pieces is measured before machining, the measurement is difficult to be reflected in the lamination height of the laminated iron core after being laminated, wherein there is a problem that laminated iron cores in which the lamination height of actually laminated iron core deviates from the tolerance of the set height are produced.
In addition, conventionally, there were cases where iron core pieces were laminated, the laminate assembly was pressurized, the height of the laminated iron cores in a caulked and fixed state was measured, and the setting of the number of thin plates to be laminated of laminated iron cores was changed based on a difference between the measurement lamination height and the set height. The setting change of the number of thin plates to be laminated of laminated iron cores was not an automated process in the production line, but was carried out based on the measurement value obtained by an operator having measured the height of the laminated iron cores after having been taken out from the production line. Therefore, the timing of reflecting the measurement data in the lamination process in the production line was delayed, resulting in a number of non-conforming articles, wherein such a problem occurred by which the yield of the products was worsened.